The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of manufacturing a shallowly diffused layer having a refractory metal silicide thereon.
A refractory metal silicide technology employs the refractory metal silicide such as a molybdenum silicide provided on deffused wiring layers in a silicon substrate or on source and drain regions of an insulated gate field effect transistor (hereinafter called as "IGFET). It has been widely used in integrated circuits of silicon, because, it can reduce the resistance of the diffused wiring layers, etc. In this technology, metals having high-melting point such as mylybdenum, tungsten, titanium and so forth are employed as refractory metals.
However, in the prior art this technology, diffused regions such as source, drain regions cannot be shallowly formed. When the refractory metal silicide is formed, the dopant impurity of N or P type has already been introduced into the silicon substrate. Therefore, the dopant impurity is undesirably diffused deeply into the substrate by the heat treatment for formation of the metal silicide. For this reason, it is difficult to form a shallow region with a shallow PN junction, e.g., shallow source and drain regions in an IGFET or a shallow emitter region in a bipolar transistor. Moreover, since the dopant is undesirably diffused also by a subsequent heat treatment at 900.degree. to 1000.degree. C. for fluidizing phosphosilicate glass for an interlayer insulating film which is carried out to flatten the surface of the phosphosiliate glass film. Therefore, the fluidization of phosphosilicate glass cannot be performed, disadvantageously.